Modulating IgG effector function by Fc glycan engineering
Modulating IgG effector function by Fc glycan engineering
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DOI：
10.1073/pnas.1702173114
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发表时间：
2017-03-28
影响因子：
11.1
通讯作者：
Wang, Lai-Xi
中科院分区：
文献类型：
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作者：
Li, Tiezheng;DiLillo, David J.;Wang, Lai-Xi
IgG抗体在Fc结构域上含有保守的N-糖基化位点，其上连接有复杂的双触角聚糖。该聚糖的精细结构通过影响Fc与不同Fc受体家族成员的结合亲和力来调节抗体效应子功能。例如，核心岩藻糖基化显著降低抗体依赖性细胞毒性（ADCC），而末端α 2，6-唾液酸化在人静脉内免疫球蛋白疗法的抗炎活性中起关键作用。然而，聚糖中糖的特定组合对ADCC的影响仍有待进一步解决。因此，我们合成了具有不同岩藻糖基化和唾液酸化组合的结构明确的同质抗体糖型，并并行进行了体外Fc γ R结合分析、基于细胞的ADCC测定和体内IgG介导的细胞耗竭研究。我们发现，无论唾液酸化状态如何，核心岩藻糖基化对Fc γ RIIIA结合、体外ADCC和体内IgG介导的细胞耗竭均产生显著不良影响。相反，唾液酸化对ADCC的影响取决于核心岩藻糖基化的状态。在基于细胞的测定中，核心岩藻糖基化背景下的唾液酸化显著降低ADCC，并抑制体内抗体介导的细胞杀伤。相反，在岩藻糖基化不存在的情况下，唾液酸化不会对ADCC产生不利影响。
IgG antibodies contain a conserved N-glycosylation site on the Fc domain to which a complex, biantennary glycan is attached. The fine structures of this glycan modulate antibody effector functions by affecting the binding affinity of the Fc to diverse Fc receptor family members. For example, core fucosylation significantly decreases antibody-dependent cellular cytotoxicity (ADCC), whereas terminal alpha 2,6-sialylation plays a critical role in the anti-inflammatory activity of human i.v. immunoglobulin therapy. The effect of specific combinations of sugars in the glycan on ADCC remains to be further addressed, however. Therefore, we synthesized structurally well-defined homogeneous glycoforms of antibodies with different combinations of fucosylation and sialylation and performed side-by-side in vitro Fc gamma R-binding analyses, cell-based ADCC assays, and in vivo IgG-mediated cellular depletion studies. We found that core fucosylation exerted a significant adverse effect on Fc gamma RIIIA binding, in vitro ADCC, and in vivo IgG-mediated cellular depletion, regardless of sialylation status. In contrast, the effect of sialylation on ADCC was dependent on the status of core fucosylation. Sialylation in the context of core fucosylation significantly decreased ADCC in a cell-based assay and suppressed antibody-mediated cell killing in vivo. In contrast, in the absence of fucosylation, sialylation did not adversely impact ADCC.